Type action



1962 J. A. ENDERS 3,021,934

TYPE ACTION Filed March 17, 1960 2 Sheets-Sheet 1 Fig.1 42

INVENTOR F 19.2 JOHN A. ENDERS ATI'ORN EYS J. A. ENDERS 7 Feb. 20, 1962 TYPE ACTION 2 Sheets-Sheet 2 Filed March 17, 1960 INVENTOR JOHN A. ENDERS Fig.4

ATTORNEYS United Statesv Patent Ofilice 3,021,34 Patented Feb. 20, 162

35321534 TYPE AQTIGN John A. Enders, Simshury, onn., assignor to Royal Mc- Bee Corporation, Port Chester, N.Y., a corporation of New York Filed Mar. 17, 1960, Ser. No. 15,653 7 Claims. (Cl. 1197-47) This invention relates to an improved type action for business machines and more particularly relates to a novel arrangement for controlling the operative engagement of a type bar linkage actuating pawl with the power roll of an electric typewriter.

In electric typewriters which employ a serrated or grooved power roll, the printing stroke of any given type bar is initiated by permitting the associated trip pawl to move into operative engagement with the teeth of the rotating power roll. It has been found that occasionally in this type of action the roll engaging tooth of the pawl may not properly engage the power roll teeth with the result that the associated type bar is improperly actuated. This latter condition may give rise to dropped character, or to uneven impressions due to incomplete type bar drive actions.

One object of the present invention is to provide .an improved type action for electric typewriters whereby a type bar trip pawl is controllably engaged with the power roll.

Another object of the invention is to provide a novel type action for electric typewriters whereby the type bar actuating pawls may be positively moved into operative engagement with the power roll.

A further object of the invention is to provide an improved type bar actuating trip pawl arrangement for electric typewriters whereby a dog movably mounted on the trip pawl is adapted to initially engage the power roll and thereby operate the trip pawl so that the latter is power driven into engagement with said power roll.

Still another object of the invention is to provide two roll engaging members for each type action of an electric typewriter whereby at least one of said members is always in a position to move into assured operative engagement with the teeth of the power roll.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein:

FIGURE 1 is a side elevational view in partial section and shows the normal condition of the parts of a type. action embodying the instant invention.

' FIGURES 2, 3 and 4 are side elevational views illustrating three active conditions of the apparatus of FIG- URE 1.

The instant invention will be shown and'described as embodied in an electric typewriter of the type now being produced and sold by the Royal McBee Corporation. It will be understood however that the present invention may be utilized in connection with any of the various other types of typewriters that have rotating power rolls. Unless otherwise indicated it will be assumed that the various parts illustrated are suitably supported by the main frame of the machine.

Referring to FIGURE 1 there is shown an illustrative type action comprising a conventional key operated linkage ill and type bar actuating linkage 11. The linkage It comprises a key lever 12 which is pivotally mounted as at 13 on the machine frame 14 and which has an upwardly extending arm 15 provided with a bent-off portion 16 that is disposed immediately to the rear of the depending arm 17 of bell crank 18. Bell crank 18 is pivotally mounted as at 29 on the machine frame and is provided with a rearwardly extending arm 21 which pivotally supports an L-shaped trip member 22. The member 22 is normally biased by a spring 23 to a normal clockwise position as determined by the engagement of the upper edge of said member with a bent-off ear 24 formed on the bell crank arm 21. The key lever 12 and bell crank 18 are normally biased to their FIGURE 1 positions by means of a spring 25. The type bar actuating linkage 11 comprises an action plate having a forward end which is disposed in slots formed in the rearwardly extending upper and lower legs 31 and 32 of a comb 33 and which is yieldably biased in an upward direction by a spring 34. The upward limit of movement of the forward end of action plate 30 is determined by engagement of the bent-off plate ear 35 with the upper leg 31 of comb 33, while the downward limit of movement thereof is determined by engagement of a depending plate projection 36 with a cross member 37 secured between the side portions of the machine frame. The rearward end of the action plate 30 is articulately connected to a sub-lever ill which is pivotally mounted as at 41 on the machine frame. The upper end of the sub-lever is articulately connected to a type bar 42 through a link 43. A type bar return spring not shown maintains the linkage 11 in a normal condition such that the outer end of the type bar 42 is supported by the head rest 44 and the said forward end of action plate Si) is in the rearward portion of said comb slots as illustrated in FIGURE 1. A transversely extending trip pawl restoring member 45 is secured to the machine frame. The construction and operation of the above described apparatus is more or less conventional in nature and needs no further explanation here.

Improved means are provided for coupling the type bar actuating linkage 11 to the continuously rotating serrated power roll 46 of the typewriter, these means comprising a trip pawl 50, FIGURE 1, having a roll engaging tooth 51 formed thereon. The pawl is pivotally mounted on the action plate 30 by means of a stud 52 and is rotatably biased by a spring 53 to a normal counter clockwise position determined by engagement of the upper edge of the pawl and a bent-ofi car 54 formed on the action plate. A dog 55 is pivotally mounted on the trip pawl 50 by means of a stud 56 and has a roll engaging tooth 57 formed at the lower end thereof. The upper end of the dog is formed with a bent-off ear 60 which extends laterally through a slot 61 formedin the action plate 30 and which underlies the lower edge of said trip member 22. Dog 55 isrotatably biased by a spring 62 to a normal clockwise position determined by engagement of the car 60 with the walls of said slot 61.

In operation when the key linkage 10 is operated the lowering of the trip member 22 will serve to rotate the dog 55 against the action of spring 62 so that the tooth 57 thereof moves into operative engagement with the teeth of the continuously rotating power roll 46, as illustrated in FIGURE 2. Once this engagement is effected, continued rotation of the power roll will cause the now. slightly displaced dog 55 to be positively displaced downwardly against the action of springs 53 and 62 thereby power operating the trip pawl 50 so as to pull the roll engaging pawl tooth 51 into operative engagement with the power roll. Thereafter the action plate 30, together with the pawl 56 and dog 55 are power driven forwardly to affect an operative printing stroke of the type bar 42. During the initial downward and forward movement of the action plate 30 the resultant translation of the dog 55 will cause the tooth 57 of the latter to be disengaged '3 3 from the power roll, as illustrated in FIGURE 4, while the pawl tooth 51 is frictionally retained in driving engagement with the power roll against the pawl restoring action of the spring 53. During the operative stroke of the action plate the pawl 58 becomes disengaged from the power roll in the usual manner and the springs 53 and 62 then tend to restore the pawl 50 and dog 55 to their respective normal FIGURE 1 positions on the action plate. Near the end of the forward stroke of the action plate the spring 34 will elevate the lowered forward end of the action plate until the action plate ear 35' again engages the lower surface of the upper leg 31 of comb 33. If the springs 53 and 62 have not already restored said pawl and dog to their normal positions on the action platethen the upward movemenut of the action plate will cause the forward edge 65 of the pawl to engage the said member 45 so as to assist in the restoration of said pawl and dog to said normal positions.

It will be noted from FIGURE 2 that when the dog tooth 57 is operatively engaged with a power roll tooth the pawl tooth 51 will be operatively disposed so as to be capable of properly engaging the power roll when pulled toward such by the action of the driven dog 55. If, when the dog 55 is initially operated by the key linkage 10, the dog tooth 57 is in a position only slightly removed from the operative coupled condition of FIG- URE 2 so that it momentarily initially engages the outer tip of the adjacent power roll tooth, as illustrated in FIG- URE 3, then the downward force exerted on dog 55 by the key linkage will directly act to cause the pawl to be displaced in a clockwise direction into assured operative engagement with the power roll. If the manually displaced pawl tooth 51 should here initially engage the outer tip of a roll tooth then the dog tooth 57 would be disposed between two adjacent power roll teeth and will be free to swing into operative engagement with the power roll. Thus by making the operative arcuate distance between the roll engaging positions of the dog and pawl teeth 51 and 57 unequal to a multiple of the circumferential pitch of the teeth of the power roll, then at least one of said two teeth will always be in a position so as to be capable of being operatively engaged with the power roll teeth. In this way it is virtually impossible to obtain anything but a proper engagement of the power roll by the type bar actuating trip pawl 50.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration only and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

The invention claimed is:

1. In a typewriter having a frame, a type bar actuating linkage movably mounted on said frame, a power roll, and a key operated linkage adapted to control the operative engagement of said actuating linkage and said power roll; the improvement comprising a trip pawl movably mounted on said type bar actuating linkage, and means movably mounted on said pawl adapted to be moved relative to said pawl and into operative engagement with said power roll for immediately and positively driving said pawl into operative engagement with said power roll.

2. In a typewriter having a frame, a type bar actuating linkage movably mounted on said frame, a rotatably driven power roll, and a key operated linkage adapted to control the operative engagement of said actuating linkage and said power roll; the improvement comprising a trip pawl pivotally mounted on said type bar actuating linkage, and a member pivotally mounted on said pawl and controlled by said key operating linkage for movement into operative engagement with said power roll so as to thereby pull said trip pawl into operative engagement with said power roll.

I 3. Apparatus as defined by claim2 wherein the operative distance between the power roll engaging portions of said pawl and member is such that at least one of the said portions is always disposed between adjacent teeth of the power roll during the roll engaging operation.

4. In a typewriter having a frame, a type bar actuating linkage movably mounted on said frame, a rotatably driven power roll, and a key operated linkage adapted to control the operative engagement of said actuating linkage and said power roll; the improvement comprising a trip pawl movably mounted on said type bar actuating linkage and disposed adjacent said power roll, a dog movably mounted on said trip pawl, and spring means biasing said trip pawl and dog away from engagement with said power roll, said dog being movable into operative engagement with said power roll under the control of said key operated linkage so as to thereby power drive said trip pawl into engagement with said power roll.

5. Apparatus as defined by claim 4 wherein the operative distance bteween the power roll engaging portions of said pawl and dog is such that at least one of said portions is always disposed between adjacent teeth of the power roll during the roll engaging operation.

6. In a typewriter having a frame, a type bar actuating linkage movably mounted on said frame, a rotatably driven power roll, and a key operated linkage adapted to control the operative engagement of said actuating linkage and said power roll; the improvement comprising a trip pawl pivotally mounted on said type bar actuating linkage and having a roll engaging tooth formed thereon, a dog pivotally mounted on said trip pawl and having a roll engaging tooth formed thereon, and spring means biasing said dog and pawl away from operative engagement with said power roll, said key operated linkage being operable to pivotally displace said dog against the action of said spring means so that the dog thereby operatively engages said power roll and power drives said pawl into operative engagement with the power roll.

7. Apparatus as defined by claim 6 wherein the operative distance between the power roll engaging teeth of said pawl and dog during their roll engaging operations is such that at least one of the said teeth is always disposed between adjacent teeth of the power roll, and wherein the rotational axis of said dog is offset and parallel with respect to the rotational axis of said pawl.

References Cited in the file of this patent UNITED STATES PATENTS 1,789,661 Schulze Jan. 20, 1931 2,411,496 Handley Nov. 19, 1946 2,896,765 Enders July 28, 1959 

